1. Field of the Invention
The present invention relates to a structure and a control method of a data processing apparatus, for efficiently transmitting a packet according to a using order of the modules, and a computer-readable storage medium.
2. Description of the Related Art
A data processing apparatus in which a plurality of modules is communicably connected with each other and performs parallel processing can realize efficient data processing in each module by transferring a packet according to its priority.
Japanese Patent Application Laid-Open No. 11-167560 discusses a data processing apparatus, in which a plurality of modules including buffers or memories having one or more stages is connected with each other in a ring shape to form a ring bus, the same number of packets as the number of the modules are arranged in the ring bus, and data processing is performed while the packets arranged between the modules are transferred in parallel. In Japanese Patent Application Laid-Open No. 11-167560, transfer according to the priority can be realized by determining the priority by collective management.
Japanese Patent Application Laid-Open No. 2007-316699 discusses a method for transferring packets according to the priority arranged for each module. More specifically, two ring buses, namely a data transfer bus and a response transfer bus connect the modules. When it is determined that the packet that has been already transferred to the ring bus has the lower priority than the packet to be transmitted by the module, the packet that has been already transferred to the ring bus is discarded. Then, the packet having the higher priority of transmission is transmitted to the ring bus. Since the currently transferred packet is discarded, a module notifies another module of discard of the packet using the response transfer bus. The other module notified the discard of the packet transmits another packet to a transmission source. As described above, the transfer of the packet according to the priority has been realized.
According to the method discussed in Japanese Patent Application No. 11-167560, when the data transfer according to the priority is realized by the collective management, a control circuit becomes complicated and a size thereof is increased in proportion to increase in the number of the modules.
According to the method discussed in Japanese Patent Application Laid-Open No. 2007-316699, until the module can determine that the packet transmitted thereby is not discarded by other modules, all the modules are to copy all packets transmitted thereby and stores the copied packets therein. Therefore, a capacity of a buffer for storing the copies of the transmitted packets is remarkably increased in proportion to the increase in the number of the modules.